Various hydroalkylation processes are known in the art. For example, benzene and hydrogen may be contacted in the presence of a hydroalkylation catalyst to form cyclohexylbenzene. In some applications, the hydroalkylation catalyst comprises a hydrogenation metal (e.g., Pd and others) and a molecular sieve (e.g., Beta, MCM-22, MCM-49, MCM-56 and others). Other hydroalkylation catalysts may also be used.
It has been discovered that impurities in the hydrogen and/or benzene feed streams can adversely affect the performance of the hydroalkylation catalyst. For example, and as illustrated in FIGS. 1 and 2 (with reference to Examples 1 and 2), the inventors have discovered that the presence of COx compounds (e.g., carbon monoxide) and sulfur compounds (e.g., hydrogen sulfide and carbonyl sulfide) in the hydrogen feed stream adversely affects the performance of the hydroalkylation catalyst.
Similarly, and as illustrated in FIGS. 3 and 4 (with reference to Examples 3 and 4), the presence of sulfur compounds (e.g., diphenylsulfide) in the benzene feed adversely affects the performance of the hydroalkylation catalyst.
As such, what is needed is a process for treating hydrogen and/or benzene reactant streams to remove at least a portion of the impurities, thereby increasing the efficacy and prolonging the life of the hydroalkylation catalyst.